jq: error: syntax error, unexpected IDENT, expecting $end (Unix shell quoting issues?) at

cat explorer/connection-profile/test-network.json | jq ".organizations.Org1MSP.adminPrivateKey.path |= 44ab"jq: error: syntax error, unexpected IDENT, expecting $end (Unix shell quoting issues?) at <top-level>, line 1:.organizations.Org1MSP.adminPrivateKey.path|=44ab                                               jq: 1 compile error

but it works fine with

cat explorer/connection-profile/test-network.json | jq ".organizations.Org1MSP.adminPrivateKey.path |= 44"

Why?

Actually I am trying to use

cat explorer/connection-profile/test-network.json | jq ".organizations.Org1MSP.adminPrivateKey.path |= ${PRIV_KEY}"

where the ${PRIV_KEY} is 44ab..._sk